Two-dimensional amphiphilic polymer coating, coating and preparation method

Abstract

The present invention discloses a two-dimensional amphiphilic polymer coating, a coating, and a preparation method. The polymer coating is obtained by modifying a two-dimensional polycarboxylate / polycarboxylic acid by grafting alkyl chains. The amphiphilic polymer coating of the present invention increases the distribution density of hydrophilic groups in the two-dimensional plane through the large specific surface area of ​​the two-dimensional polymer, achieves an optimal balance between hydrophilicity and hydrophobicity, significantly improves adhesion to the plastic surface, and imparts durable anti-fog properties to the coating, while also exhibiting excellent wear and scratch resistance. The preparation methods of the coating and coating are simple, low-cost, and suitable for industrial-scale applications.

Description

Technical Field

[0001] The present invention relates to a polymer coating, in particular to a two-dimensional amphiphilic polymer coating, and also to a polymer coating and a preparation method, belonging to the technical field of coating materials. Background Art

[0002] Due to their excellent optical properties, transparent materials are widely used in industrial and civilian applications, such as solar cell glass, automotive windshields, glass curtain walls, medical goggles, eyewear, and light-transmitting films. However, in cold winters or when there are temperature swings, the surface of these materials often fogs up, significantly reducing their transparency and affecting their effectiveness. Therefore, developing methods to prevent fogging in transparent materials is of great significance to people's daily lives.

[0003] To date, there are two main approaches to addressing the fogging problem on transparent surfaces. The first involves disrupting the environmental conditions on the fogging surface, causing the condensed mist droplets to re-convert into water vapor, thereby restoring the optical properties of the transparent material. This approach typically requires specialized equipment and incurs additional energy consumption, resulting in limited versatility and portability, and significantly restricting its application.

[0004] Another approach is to alter the substrate's affinity for water droplets. Once formed, the droplets can quickly roll off, be absorbed, or evenly spread across the substrate surface, eliminating the negative impact of the droplets on the substrate's optical properties. Hydrophilic anti-fog coatings, which encourage droplets to spread evenly across the substrate surface, have garnered extensive attention and research, and are considered the most promising anti-fog method.

[0005] Research on superhydrophilic anti-fog coatings has made significant progress in recent years, but challenges remain that hinder their large-scale application. Specifically, the coatings' short service life makes it difficult to maintain their anti-fog effects in real-world applications. This problem is primarily due to numerous conflicts between the characteristics of the substrate and coating, and the application environment. For example, substrates requiring anti-fog coatings require high light transmittance, so the thickness of the anti-fog coating must be strictly controlled to maintain the substrate's excellent light transmittance. Transparent substrates have smooth surfaces, making it difficult for anti-fog coatings to adhere firmly to their surfaces. Furthermore, the high-surface energy components in superhydrophilic anti-fog coatings are easily reduced or even lost under external forces or even in the natural environment, resulting in poor component stability. However, coatings inevitably face abrasion, humidity, and high temperatures during application, which in turn requires high adhesion and component stability. Therefore, increasing the coating's strength while maintaining high light transmittance, improving the coating's adhesion to the substrate, and enhancing the stability of the high-surface energy components remain key research challenges for superhydrophilic anti-fog coatings.

[0006] Furthermore, developing adequate anti-fog layers for plastic substrates presents several challenges. For example, compatibility issues arise, as not all coatings work well with every type of substrate, limiting their applicability. During the anti-fog coating application process, plastic substrates often require pretreatment, such as with plasma or corona discharge. However, both plasma and corona treatments require specialized equipment and may result in the release of volatile organic compounds (VOCs) or other environmentally harmful byproducts. Furthermore, the energy consumption and maintenance costs associated with these processes can be substantial, posing economic and environmental challenges to their application on an industrial scale. Therefore, developing an anti-fog coating with strong adhesion and high durability suitable for plastic substrate surfaces without the need for pretreatment holds great promise for future applications. Summary of the Invention

[0007] In response to the shortcomings of the prior art, the first objective of the present invention is to provide a two-dimensional amphiphilic polymer coating. The two-dimensional polymer in this coating has a large specific surface area, increasing the distribution density of hydrophilic groups in the two-dimensional plane, achieving an optimal balance between hydrophilicity and hydrophobicity, significantly improving adhesion to plastic substrates, and imparting durable anti-fog properties to the coating. Furthermore, through non-covalent interactions between functional groups between the two-dimensional layers, the coating possesses excellent mechanical properties.

[0008] A second object of the present invention is to provide a method for preparing a two-dimensional amphiphilic polymer coating, which is simple, easy to operate, low-cost, and suitable for industrial production.

[0009] A third object of the present invention is to provide a polymer coating having durable and stable anti-fog properties, strong adhesion to plastic surfaces, and wear and scratch resistance.

[0010] A fourth object of the present invention is to provide a method for preparing a polymer coating, which is simple, easy to operate, and environmentally friendly.

[0011] In order to achieve the above technical objectives, the present invention provides a method for preparing a two-dimensional amphiphilic polymer coating, wherein the method comprises cationizing 5-(4-vinylbenzyloxy)isophthalic acid monomer with tetramethylguanidine, and then performing a polymerization reaction to obtain a two-dimensional polycarboxylic acid product; and esterifying the two-dimensional polycarboxylic acid product with a haloalkane to obtain;

[0012] The 5-(4-vinylbenzyloxy)isophthalic acid monomer is prepared by a substitution reaction between 5-hydroxydimethylisophthalate and 4-vinylbenzyl chloride to obtain a 5-(4-vinylbenzyloxy)isophthalic acid dimethyl monomer, which is then hydrolyzed and acidified.

[0013] The present invention utilizes hydrophilic carboxylate monomers through free radical polymerization to produce a two-dimensional polycarboxylic acid / polycarboxylate. This two-dimensional polymer has a large specific surface area and contains a large number of hydrophilic groups on the polymer surface, resulting in super-hydrophilic properties. However, the high surface energy components in the super-hydrophilic anti-fog coating are easily reduced or even lost under external forces or even in natural environments, resulting in poor component stability. Therefore, the present invention further grafts hydrophobic alkyl chains onto the surface through an esterification reaction, effectively adjusting the hydrophilicity and hydrophobicity of the two-dimensional polymer surface. This reduces the forces between the two-dimensional layers, significantly improving the adhesion and mechanical properties of the film; it also reduces the surface energy of the polymer coating, improving the coating's long-lasting anti-fog performance, and thus significantly extending the coating's service life. Furthermore, grafting alkyl chains onto the two-dimensional carboxylic acid polymer creates a certain degree of roughness on the coating surface, increasing the coating's surface area and further enhancing mechanical interlocking and durability under stress. Simultaneously, the roughened surface exhibits a series of nanoscale rough structures that act as nucleation centers, promoting the formation of smaller water droplets and reducing light scattering, thereby improving anti-fog performance.

[0014] As a preferred embodiment, the molar addition amount of the monohalogenated alkyl is 20% to 80% of the two-dimensional polycarboxylic acid product, more preferably 30% to 70%. The amount of alkyl halide added determines the grafting rate of the alkyl chains; a greater amount of alkyl halide added results in a higher grafting rate. Controlling the grafting rate within an appropriate range ensures that the coating maintains both good anti-fog and scratch resistance. Too low a grafting rate reduces the coating's mechanical properties, especially scratch resistance, while too high a grafting rate diminishes the anti-fog effect.

[0015] As a preferred solution, the halogen element in the monohalogenated alkane includes one of Cl, Br, and I.

[0016] As a preferred embodiment, the number of carbon atoms in the alkyl chain of the monohalogenated alkane is 3 to 9, more preferably 4 to 8. Controlling the alkyl chain length within an appropriate range can improve the overall performance of the coating. The shorter the alkyl chain, the better the anti-fog properties of the modified coating. However, shorter alkyl chains do not improve the mechanical properties of the polymer, resulting in poor abrasion resistance and adhesion of the coating. Longer alkyl chains create larger intermolecular spaces within the coating, allowing water molecules to accumulate, resulting in the formation of fine mist droplets on the coating surface and a decrease in anti-fog performance.

[0017] As a preferred solution, the two-dimensional polycarboxylic acid product is prepared as a solution for the esterification reaction, and the mass concentration of the two-dimensional polycarboxylic acid product solution is 5% to 20%.

[0018] As a preferred solution, the esterification reaction conditions are: using tetramethylguanidine as a catalyst, the temperature is 20-45° C., and the time is 10-15 h.

[0019] As a preferred solution, the polymerization reaction is carried out under a redox free radical initiation system.

[0020] As a preferred solution, the reaction solution after the polymerization reaction is dialyzed using a dialysis bag with a molecular weight cut-off of 8000, and the resulting dialyzate is freeze-dried to obtain a two-dimensional polycarboxylate. The two-dimensional polycarboxylate can be acidified to obtain a two-dimensional polycarboxylic acid.

[0021] As a preferred solution, the number average molecular weight of the two-dimensional polycarboxylic acid product is 17,000-31,000.

[0022] As a preferred solution, the molar amount of tetramethylguanidine added is 0.8 to 1.2 times that of the 5-(4-vinylbenzyloxy)isophthalic acid monomer.

[0023] As a preferred solution, the reducing agent in the redox free radical initiation system is thiosulfate, and the oxidizing agent is persulfate.

[0024] As a preferred embodiment, the molar addition amount of the thiosulfate is 0.03 to 0.08 times that of the 5-(4-vinylbenzyloxy)isophthalic acid monomer.

[0025] As a preferred solution, the molar addition amount of the persulfate is 0.04 to 0.09 times that of the 5-(4-vinylbenzyloxy)isophthalic acid monomer.

[0026] As a preferred embodiment, the thiosulfate is sodium thiosulfate.

[0027] As a preferred solution, the persulfate is potassium persulfate.

[0028] As a preferred solution, after adding the reducing agent and reacting for 0.5 to 2 hours, the oxidizing agent is added and the reaction is continued for 6 to 24 hours.

[0029] As a preferred embodiment, the preparation process of the 5-(4-vinylbenzyloxy)isophthalic acid monomer is as follows: 5-hydroxydimethyl isophthalate, 4-vinylbenzyl chloride, potassium iodide and DMF are mixed and stirred, and potassium carbonate is added to carry out a substitution reaction to obtain 5-(4-vinylbenzyloxy)isophthalic acid dimethyl ester monomer; the 5-(4-vinylbenzyloxy)isophthalic acid dimethyl ester monomer is dissolved in ethanol and then sodium hydroxide solution is added to carry out a hydrolysis reaction; the obtained reaction product is acidified with hydrochloric acid to obtain 5-(4-vinylbenzyloxy)isophthalic acid.

[0030] The reaction principle involved in the preparation process is as follows:

[0031] (1);

[0032] (2).

[0033] The present invention also provides a two-dimensional amphiphilic polymer coating, which is prepared by the above method.

[0034] The present invention also provides a method for preparing a polymer coating, which comprises immersing a substrate in a solution containing the two-dimensional amphiphilic polymer coating and then performing surface drying treatment to obtain the polymer coating.

[0035] As a preferred solution, the mass concentration of the two-dimensional amphiphilic polymer coating solution is 1% to 5%.

[0036] As a preferred solution, the soaking temperature is room temperature and the soaking time is 8 to 15 minutes.

[0037] As a preferred solution, the substrate includes LDPE, PC, PET, glass, etc.

[0038] The present invention also provides a polymer coating, which is prepared by the above method.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) By forming a modified amphiphilic polymer by grafting alkyl chains of two-dimensional polycarboxylate / polycarboxylic acid, the polymer achieves an optimal balance between hydrophilicity and hydrophobicity, improving adhesion to the plastic surface and effectively overcoming the major disadvantage of ordinary polymer anti-fog coatings, that is, super-hydrophilic polymers are conducive to anti-fog, but are easy to swell or dissolve, losing anti-fog performance;

[0041] (2) The prepared polymer coating has a long-lasting anti-fog effect, good mechanical properties, wear resistance and scratch resistance, high stability, good adaptability to various substrates, strong adhesion to plastic substrates, and no pretreatment of the plastic substrate is required, such as plasma or corona discharge, which significantly reduces production costs and reduces the release of volatile organic compounds (VOCs) or other environmentally harmful byproducts;

[0042] (3) The preparation method is simple, easy to operate, low cost, and suitable for industrial-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is the H NMR spectrum of the carboxylic acid monomer prepared in Example 1.

[0044] Figure 2 This is the H-NMR spectrum of the two-dimensional polycarboxylic acid polymer prepared in Example 1.

[0045] Figure 3The thermal fog experiment results of glass with the coating prepared in Example 3 and without the coating are shown.

[0046] Figure 4 The microscopic morphology comparison diagram of the coatings prepared in Example 1, Example 3 and Comparative Example 1 after the scratch test. DETAILED DESCRIPTION

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0048] Example 1

[0049] (1) Synthesis of carboxylic acid monomer

[0050] Weigh dimethyl 5-hydroxyisophthalate (2.10 g, 10 mmol) and potassium iodide (0.332 g, 2 mmol) into a reaction flask, add 4-vinylbenzyl chloride (1.8 mL, 10 mmol), and finally DMF (10 mL). Slowly add potassium carbonate (3.317 g, 24 mmol) while stirring. The temperature was raised to 40°C and allowed to react overnight. After the reaction, dichloromethane (20 mL) was added, and the mixture was extracted three times with distilled water. The organic layer was dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure, and the resulting yellow solid was ultrasonically cleaned with methanol and filtered. This process was repeated several times to obtain a white solid, which was then dried under vacuum to obtain the carboxylate monomer (dimethyl 5-(4-vinylbenzyloxy)isophthalate).

[0051] The carboxylate monomer (3.12 g, 10 mmol) was weighed into a reaction flask, and ethanol (20 mL) was added and heated to dissolve. A solution of sodium hydroxide (1.80 g, 20 mmol) in water (10 mL) was then added with stirring, and the mixture was heated to 80°C and refluxed for reaction. The resulting solution was a transparent yellow color. The ethanol was evaporated under reduced pressure and then acidified with dilute hydrochloric acid. The precipitate was collected by filtration and rinsed with copious amounts of water and ethanol to obtain the carboxylic acid monomer (5-(4-vinylbenzyloxy)isophthalic acid). Its H NMR spectrum showed Figure 1 .

[0052] (2) Synthesis of two-dimensional polymers

[0053] .

[0054] The carboxylic acid monomer (0.284 g, 1 mmol) was weighed and added to water (10 g) containing TMG (1 mmol) and stirred to dissolve to obtain a clear solution. After three ventilation operations of freezing-evacuating-thawing-filling with nitrogen, the temperature was controlled at 30 ° C, the magnetic stirrer was 500 r / min, and the reducing agent sodium thiosulfate pentahydrate (0.012 g, 0.05 mmol) was added to react for 1 hour, and then the oxidizing agent potassium persulfate (0.016 g, 0.06 mmol) was added to continue the reaction for 23 hours. After the polymerization reaction, the polymer solution was transferred to a dialysis bag with a molecular weight cutoff of 8000 and dialyzed for one week. The dialysis solvent was water, which was changed 5 times a day. The dialysate was frozen with liquid nitrogen and then vacuum freeze-dried to obtain a two-dimensional polycarboxylate. The two-dimensional polycarboxylate was acidified with hydrochloric acid to obtain a two-dimensional polycarboxylic acid. The nuclear magnetic hydrogen spectrum of the two-dimensional polycarboxylic acid polymer is shown in Figure 2 , where line 1 is the H-NMR spectrum of the two-dimensional polymer, and line 2 in the partially enlarged image is the H-NMR spectrum of the carboxylic acid monomer before polymerization.

[0055] (3) Grafting surface modification of two-dimensional polycarboxylic acid / carboxylate polymers

[0056] The above-mentioned two-dimensional polymer was prepared into a solution with a mass concentration of 10% (the solvent was water), and 1-bromopropane (C3) was added, wherein the molar amount of bromopropane was 0.6 times that of the two-dimensional polymer (calculated as carboxylate functional groups) (grafting rate 60%), and then an equal molar amount of tetramethylguanidine was added relative to the polymer. After reacting at 35°C for 12 hours, the mixture was freeze-dried to obtain an alkyl chain-modified two-dimensional polycarboxylic acid polymer.

[0057] (4) Polymer coating

[0058] The above-mentioned alkyl chain-modified two-dimensional polycarboxylic acid polymer was prepared into a 1% aqueous solution, and the PC sheet was immersed in the solution for 10 minutes. The substrate was then removed and dried for 30 seconds. The surface of the substrate was then cleaned with deionized water and ethanol, and then dried in an oven at 45°C for 24 hours to obtain a polymer coating.

[0059] Example 2

[0060] The modified two-dimensional polymer was prepared using the method of Example 1, except that the bromoalkane was 1-bromobutane (C4). The coating was prepared in the same manner as in Example 1.

[0061] Example 3

[0062] The modified two-dimensional polymer was prepared using the method of Example 1, except that the bromoalkane was 1-bromohexane (C6). The coating was prepared in the same manner as in Example 1.

[0063] Example 4

[0064] The modified two-dimensional polymer was prepared using the method of Example 1, except that the bromoalkane was 1-bromooctane (C8). The coating was prepared in the same manner as in Example 1.

[0065] Example 5

[0066] The modified two-dimensional polymer was prepared using the method of Example 1, except that the bromoalkane was 1-bromononane (C9). The coating was prepared in the same manner as in Example 1.

[0067] Example 6

[0068] The modified two-dimensional polymer was prepared using the method of Example 3, except that the molar amount of 1-bromohexane (C6) added was 0.2 times that of the two-dimensional polymer (grafting rate 20%). The coating was prepared in the same manner as in Example 3.

[0069] Example 7

[0070] The modified two-dimensional polymer was prepared using the method of Example 6, except that the molar amount of 1-bromohexane (C6) added was 0.3 times that of the two-dimensional polymer (grafting rate 30%). The coating was prepared in the same manner as in Example 3.

[0071] Example 8

[0072] The modified two-dimensional polymer was prepared using the method of Example 6, except that the molar amount of 1-bromohexane (C6) added was 0.4 times that of the two-dimensional polymer (grafting rate 40%). The coating was prepared in the same manner as in Example 3.

[0073] Example 9

[0074] The modified two-dimensional polymer was prepared using the method of Example 6, except that the molar amount of 1-bromohexane (C6) added was 0.7 times that of the two-dimensional polymer (grafting rate 70%). The coating was prepared in the same manner as in Example 3.

[0075] Example 10

[0076] The modified two-dimensional polymer was prepared using the method of Example 6, except that the molar amount of 1-bromohexane (C6) added was 0.8 times that of the two-dimensional polymer (grafting rate 80%). The coating was prepared in the same manner as in Example 3.

[0077] Comparative Example 1

[0078] The coating was prepared by the method of Example 1, except that the polymer was a two-dimensional polycarboxylate that had not been modified, and other conditions remained unchanged.

[0079] The performance tests were performed on the coatings prepared in the examples and comparative examples, and the results are shown in Table 1.

[0080]

[0081] Hydrophobicity Angle Test Method: The static contact angle of the coating was measured using a JGW-360a contact angle meter. The test liquid volume was 2µL, the test environment was 24±1°C, and the relative humidity was 45±1%. The water droplet contact angle was measured at five points and the average value was taken.

[0082] Sandpaper abrasion test: After the water fumigation test, tie a 35g weight to a cork ruler, place the coated side of the sample against the sandpaper, and move the ruler used to fix the sample along the sandpaper 10cm for a total of 5 times.

[0083] As can be seen from the data in Table 1, the polymer coating prepared according to the present invention exhibits excellent anti-fog and scratch resistance compared to Comparative Example 1. The data from Examples 1 to 5 show that as the number of carbon atoms in the modified alkyl chain reagent increases, the anti-fog performance of the coating decreases, while the scratch resistance increases. The data from Examples 6 to 10 show that as the grafting rate of the modified alkyl chain reagent increases, the anti-fog performance of the coating decreases, while the scratch resistance increases.

[0084] The coating prepared in Example 3 of the present invention was used to conduct a thermal fog test. Figure 3 As shown, from Figure 3 It can be seen from the figure that the glass containing the coating of the present invention still has a clear field of vision after the heat fogging treatment, while the glass without the coating is obviously fogged, that is, the coating of the present invention has an excellent anti-fogging effect.

[0085] Figure 4 The microscopic morphology of the coating after scratching is shown in Figure 1, where (1) is the coating prepared in Comparative Example 1, (2) is the coating prepared in Example 1, and (3) is the coating prepared in Example 3. As can be seen from the figure, the coating of Comparative Example 1 has obvious scratches, the coating of Example 1 has slight scratches, and the coating of Example 3 has almost no scratch marks. It can be seen that the coating prepared by the present invention has excellent scratch resistance.

Claims

1. A method for preparing a two-dimensional amphiphilic polymer coating, characterized in that: The 5-(4-vinylbenzyloxy)isophthalic acid monomer is cationized by tetramethylguanidine, and then subjected to polymerization reaction to obtain a two-dimensional polycarboxylic acid product; the two-dimensional polycarboxylic acid product is subjected to esterification reaction with a haloalkyl to obtain; The 5-(4-vinylbenzyloxy)isophthalic acid monomer is prepared by reacting 5-hydroxydimethylisophthalate and 4-vinylbenzyl chloride to obtain 5-(4-vinylbenzyloxy)isophthalic acid dimethyl monomer, and then hydrolyzing and acidifying the 5-(4-vinylbenzyloxy)isophthalic acid dimethyl monomer; The molar addition amount of the monohalogenated alkyl is 30% to 70% of the two-dimensional polycarboxylic acid product; The number of carbon atoms in the alkyl chain of the monohalogenated alkane is 4 to 8.

2. The method for preparing a two-dimensional amphiphilic polymer coating according to claim 1, wherein: The polymerization reaction is carried out under a redox free radical initiation system.

3. The method for preparing a two-dimensional amphiphilic polymer coating according to claim 2, wherein: The molar addition amount of the tetramethylguanidine is 0.8 to 1.2 times that of the 5-(4-vinylbenzyloxy)isophthalic acid monomer; The reducing agent in the redox free radical initiation system is thiosulfate, and the oxidizing agent is persulfate; The molar addition amount of the thiosulfate is 0.03 to 0.08 times that of the 5-(4-vinylbenzyloxy)isophthalic acid monomer; The molar addition amount of the persulfate is 0.04 to 0.09 times that of the 5-(4-vinylbenzyloxy)isophthalic acid monomer; The thiosulfate is sodium thiosulfate; The persulfate is potassium persulfate.

4. The method for preparing a two-dimensional amphiphilic polymer coating according to claim 2 or 3, characterized in that: After adding the reducing agent and reacting for 0.5 to 2 hours, add the oxidizing agent and continue the reaction for 6 to 24 hours.

5. The method for preparing a two-dimensional amphiphilic polymer coating according to claim 1, wherein: The halogen element in the monohalogenated alkane includes one of Cl, Br and I.

6. The method for preparing a two-dimensional amphiphilic polymer coating according to claim 1 or 5, characterized in that: The esterification reaction conditions are: using tetramethylguanidine as a catalyst, a temperature of 20-45° C., and a time of 10-15 hours.

7. A two-dimensional amphiphilic polymer coating, characterized in that: The method is prepared by any one of claims 1 to 6.

8. A method for preparing a polymer coating, characterized in that: The substrate is immersed in the two-dimensional amphiphilic polymer coating solution according to claim 7, and then subjected to surface drying treatment to obtain the substrate.

9. A polymer coating, characterized in that: Prepared by the method according to claim 8.

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